Effect of Technique of Disinfection by Ultrasonic Nebulization on Accuracy of Vinyl Polysiloxane Impressions
Marcio Jose Mendonca,
Universitaria St., 2069 ZIP 85819-110 Faculdade. Cascavel-PR Brasil, Cascavel, Parana, Brazil.
Introduction: To prevent cross-contamination, impressions should be properly disinfected after removing from the mouth. To be efficacious, a successful disinfection must maintain the physico-chemical properties of the impression materials and should not interfere negatively in the fabrication of stone casts.
Aim: To evaluate the effect of different disinfection techniques on the accuracy of dental impressions made of vinyl polysiloxane.
Materials and Methods: 40 test samples made of vinyl polysiloxane were obtained using a pattern cylinder. The samples were randomly divided into 5 experimental conditions: I-Control, impressions without any disinfection, II-Immersion in 2% glutaraldehyde for 10 minutes, III-Immersion in 0.2% peracetic acid for 10 minutes, IV-ultrasonic nebulization for 10 minutes in 2% glutaraldehyde and V-ultrasonic nebulization for 10 minutes in 0.2% peracetic acid. The impressions obtained were poured in type IV gypsum and both the height and diameter of the stone casts were measured. For this purpose a profile projector joined to a digital measurement system was used. The data were submitted to statistical analysis using Bioestat 5.3 software. The Shapiro-Wilk test was applied to assess normal data distribution. Data were analysed by one-way ANOVA and Tukeyâ€™s test for comparisons of the means of the different groups, p-value less than 0.05 was considered as statistically significant.
Results: Groups I, II and III did not differ statistically among themselves, both in diameter and height. Group IV presented statistically different results from the others for diameter. Whereas for height, the results were shown to be similar among groups I, II, III and IV. For Group V, the results obtained were statistically different for both height and diameter from those of the other groups.
Conclusion: The immersion technique did not interfere in the accuracy of the stone casts however the ultrasonic nebulization with 2% glutaraldehyde solution did not show significant differences for height and presented better values of dimensional accuracy in diameter, when compared to the control group. The ultrasonic nebulization method associated with 2% peracetic acid solution presented the worst dimensional accuracy values for height and better values for the diameter compared to the other groups.